Stretch releasing adhesive tapes and adhesive tape strips represent an emerging class of high performance pressure-sensitive adhesives combining strong holding power with clean removal and no surface damage. Such stretch releasing adhesive tapes are useful in a wide variety of assembling, joining, attaching, and mounting applications.
Stretch releasing adhesive tapes are known in the patented prior art. U.S. Pat. No. 4,024,312 (Korpman), for example, discloses a highly conformable adhesive tape including a highly extensible and elastic backing film laminated with an adhesive layer. The backing film possesses a lengthwise elongation at break of at least about 200%. The tape is easily stretchable and may be removed from a surface by stretching the tape lengthwise in a direction substantially parallel to the surface. German Patent No. 33 31 016 discloses a high elasticity, low plasticity adhesive film based on a thermoplastic rubber and tackifying resins, wherein the adhesive bond can be broken by stretching the adhesive film in the direction of the plane of the adhesive bond.
Adhesive tape strips with non-adhesive pull tabs are also known. U.S. Pat. No. 5,516,581 (Kreckel et al.), for example, discloses a removable adhesive tape having a highly extensible and substantially inelastic backing coated with a layer of pressure sensitive adhesive and a non-adhesive pull tab to facilitate stretch removal. The adhesive tape can be removed from a substrate without damaging the substrate by grasping the non-adhesive pull tab and stretching the tape in a direction substantially parallel to the surface of the substrate. The tape backing has a lengthwise elongation at break of from about 150% to about 1200%, a Young's modulus of at least about 2,500 psi to about 72,500 psi, and an elastic recovery of less than about 50% after being stretched and removed.
U.S. Pat. No. 6,231,962 (Bries et al.) discloses a removable foam adhesive tape with a non-adhesive pull tab. The adhesive tape comprises a backing including a layer of polymeric foam and a layer of pressure-sensitive adhesive coated on at least one surface of the backing. The foam layer of the backing has a thickness of about 30 to about 1000 mils, and the backing has a lengthwise elongation at break of from about 50% to about 1200%, and a Young's modulus of less than about 2,400 psi.
A commercially available stretch releasing adhesive tape is the product sold under the trade designation COMMAND by 3M Company, St. Paul, Minn. This product is currently manufactured in discrete strips with one end of the strip including a non-adhesive pull tab to facilitate stretching of the strip during removal.
While such stretch releasing strips generally work well, when the strip is used to join two or more objects, the tab portion at the end of a strip is often left exposed to allow a user who later wishes to separate the objects to grasp it. Such a projecting tab portion can be aesthetically objectionable. If one of the objects is flexible, such as a poster board, it may be bent to afford access to the tab portion. In many instances where rigid objects are joined, however, it may be necessary to allow the tab portion to project from between the joined objects to afford access to the tab portion to remove the adhesive strip from between the objects.
To conceal the tab portion, devices have been designed to selectively conceal the pull tab until stretch removal is desired. U.S. Pat. No. 5,507,464 (Hamerski et al.), for example, discloses a two-piece hook specially made with a slidable cover portion that selectively conceals the tab portion.
U.S. Pat. No. 5,725,923 (Lühmann) discloses a tape structure that can be used to bond opposed surfaces of objects including rigid objects with no portion of the tape structure projecting from between the objects, and which subsequently affords separation of the objects by moving one of the objects relative to the other. The tape structure is described as an adhesive tape for separable adhesive joints made from a double-sided adhesive tape which has adhesive areas on opposing sides at an offset which are not adherent, whereby the non adherent areas do not, or only slightly overlap, and which allow the adhesive joints made with them to be separated by pulling apart the non-adhesive areas, particularly by pulling in the direction of the adhesive plane.
U.S. Pat. No. 6,004,642 (Langford) discloses a tape structure that can be used to bond together the opposed surfaces of objects including rigid objects (e.g., to bond a plaque or framed picture to a wall) with no portion of the tape structure projecting from between the objects, and which subsequently affords easy separation of the objects without damage to either of them. The tape structure comprises an internally separable layer having opposite major anchor surfaces. The anchor surfaces are adapted to be bonded to the opposed surfaces of objects (e.g., by layers of pressure sensitive or other types of adhesive on the anchor surfaces or by other means such as heat fusion or the use of stretch releasable tape strips). The internally separable layer has an internal static shear strength in a direction parallel to its anchor surfaces that is adapted to support one of the objects to which it is attached from the other with its anchor surfaces vertically disposed (e.g., preferably has a static shear strength parallel to its anchor surfaces that is about equal to or exceeds the maximum static shear strength that pressure sensitive adhesive will develop with normal surfaces to which it can be adhered), and has an internal dynamic tensile strength in a direction generally normal to its anchor surfaces that will afford internal separation of the separable layer by pulling apart the objects it has joined without damaging the surfaces of those objects.
There remains a need, however, for a stretch releasing adhesive tape that includes a non-adhesive pull tab that can be arranged in a manner to minimize the visual impact of the pull tab when the adhesive tape is used to mount rigid objects. In addition, there exists a need for a stretch releasing adhesive tape that can be bent or otherwise shaped for certain end use applications such as the mounting of cables, wires, cords, or the like, on a wall surface.